1. Field of the Invention
This invention relates to improvements in and concerning a method for the production of platelike hydroxyapatite. More particularly, this invention relates to a method for producing with good efficiency a platelike hydroxyapatite grown along its a and b axes, exhibits excellent crystallinity, and serves as a suitable adsorbent for chromatographic devices, for example.
2. Description of the Prior Art
Recent advances in the bioindustry have led to a need for the development of techniques for the separation and purification of biopolymers such as proteins. The hydroxyapatite represented by the chemical formula Ca.sub.10 (PO.sub.4).sub.6 OH.sub.2 possesses an adsorption characteristic specific to proteins. This characteristic can be expected to enable the separation of proteins with high efficiency. This hydroxyapatite is very stable above pH 7. When it is used as an adsorbent in chromatography, therefore, the adsorbent can be cleansed effectively with an alkali. Further, this substance is insoluble in organic solvents. Owing to these outstanding features, the hydroxyapatite has been attracting widespread attention in recent years as an adsorbent useful for chromatographic devices.
The hydroxyapatite for use as an adsorbent for chromatographic devices is produced by preparing primary particles chiefly by a wet process and pelletizing the primary particles into spherical particles measuring approximately 1 to 100 .mu.m in diameter.
The hydroxyapatite particles can be made to acquire different crystal faces. It has been ascertained that the kind of protein adsorbed on the hydroxyapatite varies with the kind of the crystal faces of the hydroxyapatite.
It is, therefore, necessary to produce hydroxyapatite which possesses crystal faces, befitting the particular kind of the protein to be adsorbed.
As concerns the hydroxyapatite, certain reports such as on the manufacture of acicular hydroxyapatite preferentially grown along the c axis as by mixing low-crystallinity apatite with various additives and subjecting the resultant mixture to a hydrothermal treatment (treatment performed by application of heat under saturated vapor pressure) have been reported in the literature (M. Yoshimura, H. Suda, K. Okamoto and K. Ioku, Journal of the Chemical Society of Japan, 10, 1402(1991)).